LED lamp

ABSTRACT

An LED lamp A includes a plurality of LED modules  2  each including an LED chip  21 , and a support member  1  including a support surface  1   a  on which the LED modules  2  are mounted. The LED modules  2  include a plurality of kinds of LED modules, or a first through a third LED modules  2 A,  2 B and  2 C different from each other in directivity characteristics that represent light intensity distribution with respect to light emission directions. This arrangement ensures that the entire surrounding area can be illuminated with sufficient brightness.

TECHNICAL FIELD

The present invention relates to an LED lamp that uses a light emitting diode (hereinafter referred to as “LED”) as the light source.

BACKGROUND ART

FIG. 63 shows an example of conventional LED lamp (see Patent Document 1, for example). The LED lamp X shown in the figure includes a plate-like substrate 91, a plurality of LED modules 92 mounted on the substrate 91, a heat dissipation member 95 attached to the substrate 91, a case 93 accommodating the substrate 91, and terminals 94. The substrate 91 is provided with a wiring pattern, not shown, connected to the LED modules 92 and the terminal 94. The LED lamp X is structured such that the LED modules 92 can be turned on when the terminals 94 are fitted into inlet ports of a socket of a general-use fluorescent lighting fixture.

The general-use fluorescent lighting fixture herein refers to lighting fixtures widely used for interior lighting as the main application, and more specifically, lighting fixtures which use, for example in Japan, a commercial power supply (e.g. AC 100 v) and to which a JIS C7617 straight-tube fluorescent lamp or a JIS C7618 circular fluorescent lamp can be attached. (Hereinafter, such a general-use fluorescent lighting fixture is simply referred to as a “lighting fixture”.)

When the LED lamp X is attached to a lighting fixture on e.g. an indoor ceiling, the main light emission direction of the LED modules 92 is oriented downward. When the LED modules 92 are turned on, most part of the light emitted from the LED modules 92 is directed in the main light emission direction of the LED modules 92. Thus, sufficient brightness cannot be obtained at the surrounding area of the LED lamp X, especially near the sides of the LED lamp X.

As compared with this, general-use fluorescent lamps can emit light from almost the entire surface of the case, so that the surrounding area of the lighting fixture is uniformly illuminated to obtain sufficient brightness. Thus, as compared with general-use fluorescent lamps, the LED lamp X has a disadvantage that sufficient brightness cannot be obtained especially near the sides of the lamp.

-   Patent Document 1: JP-U-H06-54103

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The present invention has been proposed under the circumstances described above. It is therefore an object of the present invention to provide an LED lamp that can illuminate the surrounding area with sufficient brightness.

Means for Solving the Problem

According to the present invention, there is provided an LED lamp comprising a plurality of LED modules each including an LED chip and a support member including a support surface on which the LED modules are mounted. The LED modules comprise a plurality of kinds of LED modules different from each other in directivity characteristics that represent light intensity distribution with respect to a light emission direction.

In a preferred embodiment of the present invention, the plurality of LED modules include a first LED module arranged adjacent to the center of the support surface. The directivity characteristics of the first LED module are such that light intensity in the normal direction of the support surface is relatively high, as compared with other LED modules.

In a preferred embodiment of the present invention, the first LED module includes a reflector that surrounds the LED chip and that is open in the normal direction.

In a preferred embodiment of the present invention, the first LED module further includes a sealing resin that seals the LED chip. The sealing resin is filled in a space surrounded by the reflector.

In a preferred embodiment of the present invention, the dimension of the first LED module in the normal direction of the support surface of the support member is smaller than a dimension of the first LED module in the in-plane direction of the support surface.

In a preferred embodiment of the present invention, the first LED module includes a substrate on which the LED chip is mounted, and the substrate is provided with a mount terminal on a surface thereof opposite from a surface on which the LED chip is mounted.

In a preferred embodiment of the present invention, the plurality of LED modules include a second LED module arranged adjacent to an edge of the support surface. The directivity characteristics of the second LED module are such that light intensity in an outward direction within the plane of the support surface is relatively high, as compared with other LED modules.

In a preferred embodiment of the present invention, the second LED module includes a reflector that surrounds the LED chip and that is open in the outward direction within the plane of the support surface.

In a preferred embodiment of the present invention, the second LED module further includes a sealing resin that seals the LED chip. the sealing resin is filled in a space surrounded by the reflector.

In a preferred embodiment of the present invention, the second LED module includes a substrate on which the LED chip is mounted. The second LED module is mounted on the support member, with a side surface of the substrate facing the support surface of the support member.

In a preferred embodiment of the present invention, a dimension of the second LED module in an in-plane direction of the support member is larger than the dimension of the second LED module in the normal direction of the support member.

In a preferred embodiment of the present invention, the plurality of LED modules further include a third LED module arranged between the first LED module and the second LED module. The directivity characteristics of the third LED module are such that the light intensity distribution with respect to the light emission direction is relatively uniform, as compared with the first and the second LED modules.

In a preferred embodiment of the present invention, the third LED module includes a substrate on which the LED chip is mounted, and the substrate is provided with a mount terminal on a surface thereof opposite from the surface on which the LED chip is mounted.

In a preferred embodiment of the present invention, the third LED module includes a sealing resin that seals the LED chip. The sealing resin is exposed in both of the normal direction of the support surface and the in-plane direction of the support surface.

In a preferred embodiment of the present invention, the support surface has an elongated shape. A plurality of first LED modules are arranged in the longitudinal direction of the support surface adjacent to the center of the support surface. A plurality of second LED modules are arranged along edges of the support surface that are spaced from each other in the width direction. A plurality of third LED modules are arranged in the longitudinal direction at each of the regions between the first LED modules and the second LED modules.

In a preferred embodiment of the present invention, the LED lamp further comprises a case that accommodates the first through the third LED modules and the support member and allows light emitted from the first through the third LED modules to pass through while diffusing the light.

In a preferred embodiment of the present invention, the case is cylindrical.

In a preferred embodiment of the present invention, the support member comprises an insulating substrate, and the LED lamp further comprises a heat dissipation member attached to the insulating substrate at a portion opposite from the support surface.

In a preferred embodiment of the present invention, the case is formed with a projecting piece that projects inward and supports the substrate.

In a preferred embodiment of the present invention, the projecting piece is in engagement with the heat dissipation member.

Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an example of LED lamp according to the present invention;

FIG. 2 is a schematic sectional view taken along liens II-II in FIG. 1 ;

FIG. 3 is a top view of a first LED module;

FIG. 4 is a schematic sectional view taken along lines IV-IV in FIG. 3 ;

FIG. 5 is a bottom view of the first LED module;

FIG. 6 shows directivity characteristics of the first LED module;

FIG. 7 is a side view of a second LED module;

FIG. 8 is a schematic sectional view taken along lines VIII-VIII in FIG. 7 ;

FIG. 9 shows the second LED module mounted on a support substrate;

FIG. 10 shows directivity characteristics of the second LED module;

FIG. 11 is a side view showing a variation of the second LED module;

FIG. 12 is a schematic sectional view taken along lines XII-XII in FIG. 11 ;

FIG. 13 shows directivity characteristics of a variation of the second LED module;

FIG. 14 is a top view of a third LED module;

FIG. 15 is a schematic sectional view taken along lines XV-XV in FIG. 14 ;

FIG. 16 is a bottom view of the third LED module;

FIG. 17 shows directivity characteristics of the third LED module;

FIG. 18 is a view for explaining advantages of the LED lamp;

FIG. 19 shows a variation of the LED lamp;

FIG. 20 is a schematic view showing the outer configuration of a variation of the first LED module;

FIG. 21 shows directivity characteristics of the first LED module shown in FIG. 20 ;

FIG. 22 is a schematic view showing the outer configuration of a variation of the first LED module;

FIG. 23 shows directivity characteristics of the first LED module shown in FIG. 22 ;

FIG. 24 is a schematic view showing the outer configuration of a variation of the first LED module;

FIG. 25 shows directivity characteristics of the first LED module shown in FIG. 24 , designed to emit red light and green light;

FIG. 26 shows directivity characteristics of the first LED module shown in FIG. 24 , designed to emit blue light and red light;

FIG. 27 is a schematic view showing the outer configuration of a variation of the first LED module;

FIG. 28 shows directivity characteristics of the first LED module shown in FIG. 27 ;

FIG. 29 is a schematic view showing the outer configuration of a variation of the first LED module;

FIG. 30 shows directivity characteristics of the first LED module shown in FIG. 29 ;

FIG. 31 is a schematic view showing the outer configuration of a variation of the first LED module;

FIG. 32 shows directivity characteristics of the first LED module shown in FIG. 31 ;

FIG. 33 is a schematic view showing the outer configuration of a variation of the second LED module;

FIG. 34 shows directivity characteristics of the second LED module shown in FIG. 33 ;

FIG. 35 is a schematic view showing the outer configuration of a variation of the second LED module;

FIG. 36 shows directivity characteristics of the second LED module shown in FIG. 35 ;

FIG. 37 is a schematic view showing the outer configuration of a variation of the second LED module;

FIG. 38 shows directivity characteristics of the second LED module shown in FIG. 37 ;

FIG. 39 is a schematic view showing the outer configuration of a variation of the second LED module;

FIG. 40 shows directivity characteristics of the second LED module shown in FIG. 39 ;

FIG. 41 is a schematic view showing the outer configuration of a variation of the second LED module;

FIG. 42 shows directivity characteristics of the second LED module shown in FIG. 41 ;

FIG. 43 is a schematic view showing the outer configuration of a variation of the third LED module;

FIG. 44 shows directivity characteristics of the third LED module shown in FIG. 43 ;

FIG. 45 is a schematic view showing the outer configuration of a variation of the third LED module;

FIG. 46 shows directivity characteristics of the third LED module shown in FIG. 45 ;

FIG. 47 is a schematic view showing the outer configuration of a variation of the third LED module;

FIG. 48 shows directivity characteristics of the third LED module shown in FIG. 47 ;

FIG. 49 is a schematic view showing the outer configuration of a variation of the third LED module;

FIG. 50 shows directivity characteristics of the third LED module shown in FIG. 49 ;

FIG. 51 is a schematic view showing the outer configuration of a variation of the third LED module;

FIG. 52 shows directivity characteristics of the third LED module shown in FIG. 51 ;

FIG. 53 is a schematic view showing the outer configuration of a variation of the third LED module;

FIG. 54 shows directivity characteristics of the third LED module shown in FIG. 53 ;

FIG. 55 is a schematic view showing the outer configuration of a variation of the third LED module;

FIG. 56 shows directivity characteristics of the third LED module shown in FIG. 55 ;

FIG. 57 is a schematic view showing the outer configuration of a variation of the third LED module;

FIG. 58 shows directivity characteristics of the third LED module shown in FIG. 57 ;

FIG. 59 is a side view showing a variation of the LED module;

FIG. 60 shows directivity characteristics of the LED module shown in FIG. 59 ;

FIG. 61 is a side view showing a variation of the LED module;

FIG. 62 shows directivity characteristics of the LED module shown in FIG. 61 ; and

FIG. 63 is a sectional view showing an example of a conventional LED lamp.

MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention are described below with reference to the accompanying drawings.

FIGS. 1 and 2 show an example of LED lamp according to the present invention. FIG. 1 is a schematic perspective view of the LED lamp, whereas FIG. 2 is a schematic sectional view taken along lines II-II in FIG. 1 .

The LED lamp A of this embodiment includes a support substrate 1, a plurality of LED modules 2, a heat dissipation member 3, a case 4 and a pair of bases 5. The LED lamp A is to be used as attached to a general-use fluorescent lighting fixture, as a substitute for e.g. a straight-tube fluorescent lamp. When the general-use fluorescent lighting fixture is attached to e.g. an indoor ceiling, the LED lamp A is usually mounted to the lighting fixture in such a manner that the main light emission direction of the LED modules 2 is oriented downward.

The support substrate 1 supports the LED modules 2. The support substrate 1 is made of e.g. glass-fiber-reinforced epoxy resin and has an elongated plate-like shape. The mount surface 1 a of the support substrate 1 is formed with a wiring pattern, not shown, made of e.g. Cu for supplying power to the LED modules 2.

As shown in FIG. 1 , the LED modules 2 are mounted in a matrix arrangement on the mount surface 1 a. The arrangement and number of the LED modules 2 on the mount surface 1 a of the support substrate 1 shown in FIG. 1 are merely an example, and the present invention is not limited to this example. In this embodiment, the LED modules 2 comprise first, second and third LED modules 2A, 2B and 2C. The first, the second and the third LED modules 2A, 2B and 2C differ from each other in luminous intensity distribution (directivity characteristics).

FIGS. 3-5 show the first LED module 2A. The first LED module 2A includes an LED chip 21, a substrate 22, metal wiring patterns 23 and 24 spaced from each other, a wire 25, a frame 26 and a sealing resin 27. The first LED module 2A is about 1.6 mm in length, about 0.8 mm in width and about 0.55 mm in thickness. Thus, the thickness, which is the dimension in the direction normal to the mount surface 1 a, is smaller than the length and the width, which are dimensions in the in-plane direction of the mount surface 1 a.

The directivity characteristics of the LED modules 2A are such that the intensity of the light emitted from the LED chip 21 is relatively high in the direction normal to the mount surface 1 a of the support substrate 1. FIG. 6 shows the directivity characteristics of the first LED module 2A. In this directivity characteristics, the relative intensity RI is highest at the direction angle Da of 0°. In this embodiment, as shown in FIGS. 1 and 2 , the first LED modules 2A are arranged in the longitudinal direction of the support substrate 1 at the center of the support substrate 1. Each of the first LED modules 2A is arranged in such a manner that its main light emission direction corresponds to the direction normal to the mount surface 1 a.

As shown in FIG. 4 , the LED chip 21 is mounted on the mount surface 22 a of the substrate 22 via the wiring patterns 23 and 24. The LED chip 21 comprises lamination of e.g. an n-type semiconductor, a p-type semiconductor and an active layer sandwiched between these semiconductors (none of these are shown). The LED chip 21 emits blue light when it is made of e.g. a GaN-based semiconductor.

The LED chip 21 includes two electrodes (not shown) on the upper and the lower surfaces. By mounting the LED chip 21 on the obverse surface of the lead 23, the electrode on the lower surface of the LED chip 21 is electrically connected to the wiring pattern 23. As shown in FIGS. 4 and 5 , the wiring pattern 23 reaches the reverse surface 22 b of the substrate 22 through the inner surface of a recess 28 having a semicircular cross section. The wiring pattern 23 on the reverse surface 22 b constitutes a mount terminal 29 to be bonded to the wiring pattern, not shown, of the support substrate 1. The electrode on the upper surface of the LED chip 21 is connected to the wiring pattern 23, 24 via the wire 25. Thus, the electrode on the upper surface of the LED chip 21 is electrically connected to the wiring pattern 23, 24. Similarly to the wiring pattern 23, the wiring pattern 23, 24 reaches the reverse surface 22 b of the substrate 22 through a recess 28. The lead 24 on the reverse surface 22 b constitutes a mount terminal 29 to be bonded to the wiring pattern of the support substrate 1.

The frame 26 is made of e.g. a white resin and extends upward from the periphery of the mount surface 22 a. The frame 26 includes a reflective surface 26 a surrounding the LED chip 21, the wire 25 and the sealing resin 27. The reflective surface 26 a reflects the light emitted from the LED chip 21 to cause the light to travel upward. In this way, the first LED module 2A is designed as an LED module with a reflector. With this arrangement, in the first LED module 2A, the intensity of the light from the LED chip 21 which travels in the direction normal to the mount surface 1 a of the support substrate 1 is increased.

The sealing resin 27 is provided for protecting the LED chip 21 and the wire 25. The sealing resin 27 comprises e.g. a silicone resin that transmits light emitted from the LED chip 21. In the case where a fluorescent material that emits yellow light when excited by blue light is mixed in the sealing resin 27, white light can be emitted from the LED module 2. Instead of the fluorescent material that emits yellow light, fluorescent materials each of which emits green light or red light may be mixed in.

FIGS. 7 and 8 show the second LED module 2B. In FIGS. 7 and 8, the elements that are identical or similar to those of the first LED module 2A are designated by the same reference signs as those used for the first LED module. The second LED module 2B is about 3.8 mm in length, about 1 mm in width and about 0.6 mm in thickness. Thus, the thickness, which is the dimension in the direction normal to the mount surface 1 a, is smaller than the length and the width, which are dimensions in the in-plane direction of the mount surface 1 a.

As shown in FIG. 7 , in the second LED module 2B, the leads 23, 24 extend from the mount surface 22 a of the substrate 22 onto the side surface 22 c. The portion of each of the leads 23 and 24 which covers the side surface 22 c constitutes a mount terminal 29. As shown in FIG. 9 , the second LED module 2B is disposed on the support substrate 1 in such a manner that the substrate 22 is oriented sideways, and fixed to the support substrate 1 by bonding the mount terminals 29 to the wiring pattern (not shown) of the support substrate 1 using solder 30. Thus, unlike the first LED module 2A, the main light emission direction of the LED chip 21 of the second LED module 2B corresponds to the in-plane direction of the mount surface 1 a of the support substrate 1.

FIG. 10 shows the directivity characteristics of the second LED module 2B. In this figure, the direction corresponding to the direction angle Da of 0° is the outward direction within the plane of the mount surface 1 a of the support substrate 1. In the second LED module 2B, the relative intensity RI is highest at the direction angle Da of 0°, i.e., in the outward direction within the plane of the mount surface 1 a. In this embodiment, as shown in FIGS. 1 and 2 , the second LED modules 2B are arranged along the edges of the support substrate 1 that are spaced in the width direction.

As the second LED module, the second LED module 2B′ as shown in FIGS. 11 and 12 may be employed which is not provided with a frame 26 and hence does not have a reflector. In the second LED module 2B′, the sealing resin 27 is substantially trapezoidal in side view. The leads 23, 24 of the second LED module 2B′ extend from the mount surface 22 a of the substrate 22 onto the reverse surface 22 b via the side surface 22 c. In the second LED module 2B′ again, the portion of each of the leads 23 and 24 which is positioned on the side surface 22 c constitutes a mount terminal 29. FIG. 13 shows the directivity characteristics of the second LED module 2B′. As compared with the second LED module 2B, the relative intensity RI is high in a wider region in the outward direction within the plane of the mount surface 1 a.

FIGS. 14-16 show the third LED module 2C. In these figures, the elements that are identical or similar to those of the first and the second LED modules 2A, 2B are designated by the same reference signs as those used for the first and the second LED modules. The third LED module 2C is about 1.6 mm in length, about 0.8 mm in width and about 0.36 mm in thickness. Thus, the thickness, which is the dimension in the direction normal to the mount surface 1 a, is smaller than the length and the width, which are dimensions in the in-plane direction of the mount surface 1 a.

The third LED module 2C is different from the first and the second LED modules 2A, 2B in that the third LED module does not have a frame 26 on the substrate 22. That is, as shown in FIG. 15 , in the third LED module 2C, the sealing resin 27 is substantially trapezoidal in side view and its most part is exposed. Thus, in the third LED module 2C, light from the LED chip 21 is emitted not only in the main light emission direction but also obliquely or sideways at a relatively high ratio.

FIG. 17 shows the directivity characteristics of the third LED module 2C. In a strict sense, in this directivity characteristics, the relative intensity RI is not highest at the direction angle Da of 0°. As compared with the first LED module 2A, for example, the relative intensity RI at the direction angle Da of 0° is slightly lower, but the distribution of the relative intensity RI is more uniform. In this embodiment, as shown in FIGS. 1 and 2 , the LED modules 2C are aligned on the mount surface 1 a in each of the regions between the first LED modules 2A and the second LED modules 2B. Each of the third LED modules 2C is arranged such that the main light emission direction of the LED chip 21 corresponds to the direction perpendicular to the mount surface 1 a of the support substrate 1.

The heat dissipation member 3 is provided for dissipating the heat generated at the LED modules 2 and attached to the reverse side of the support substrate 1, as shown in FIGS. 1 and 2 . The heat dissipation member 3 is made of e.g. Al and has a thin block-like shape extending in the longitudinal direction of the support substrate 1.

The surface of the heat dissipation member 3 may be treated to provide insulation so that the heat dissipation member can directly support the LED modules 2. That is, the support substrate 1 may be dispensed with. In this case, a wiring pattern similar to the wiring pattern formed on the mount surface 1 a of the support substrate 1 is formed between the LED modules 2 and e.g. an insulating sheet (not shown) having insulating property. With this arrangement, it is not necessary to prepare the support substrate 1 for mounting the LED modules 2, in addition to the heat dissipation member 3, so that the cost for the parts is reduced.

The case 4 is provided for accommodating the support substrate 1, the heat dissipation member 3 and so on, and is cylindrical, as shown in FIG. 2 . The case 4 comprises a single-piece member made by extrusion of a synthetic resin such as polycarbonate. When part of the light emitted from the LED modules 2 reaches the inner surface of the case 4, the case 4 allows the light to pass through while diffusing the light.

A pair of projecting pieces 41 are formed integrally on the inner surface of the case 4 to project inward. In the state shown in FIG. 2 , part of the heat dissipation member 3 is held in engagement with the projecting pieces 41 so that the movement of the heat dissipation member 3 relative to the case 4 in a direction perpendicular to the center axis O1 (upward direction in the figure) is restricted. The support substrate 1, the heat dissipation member 3 and so on are housed in the case 4 by inserting the heat dissipation member 3 into the case 4 by sliding movement on the inner side of the projecting pieces 41.

The paired bases 5 are to be attached to a socket (not shown) of a general-use fluorescent lighting fixture to supply AC power from a commercial power supply. As shown in FIG. 1 , each of the bases 5 is provided with two terminals 51. The terminals 51 are the portions to be fitted into the insertion ports of the socket of the general-use fluorescent lighting fixture.

The advantages of the LED lamp A are described below with reference to FIG. 18 . FIG. 18 shows the cross section of the LED lamp A attached to a general-use fluorescent lighting fixture fixed to e.g. an indoor ceiling P. It is to be noted that the illustration of FIG. 18 is upside down.

According to this embodiment, when the LED lamp A is turned on, light is emitted from the LED chips 21 of the first through the third LED modules 2A, 2B and 2C. The dotted line SA shows the directivity characteristics of the first LED modules 2A.

The directivity characteristics of the first LED modules 2A are such that the intensity of light is extremely high in the direction normal to the mount surface 1 a. The dotted lines SB show the directivity characteristics of the second LED modules 2B. The directivity characteristics of the second LED modules 2B are such that the intensity of light is high in the outward direction within the plane of the mount surface 1 a. The dotted lines SC show the directivity characteristics of the third LED modules 2C. The directivity characteristics of the third LED modules 2C are such that the intensity of light is relatively uniform around a line normal to the mount surface 1 a.

In this way, since the first through the third LED modules 2A, 2B and 2C that are different from each other in light directivity characteristics are disposed on the support substrate 1 in the present embodiment, the light emitted from the LED lamp A is directed substantially uniformly in almost all directions except the direction toward the ceiling P. Thus, sufficient brightness is obtained at every point around the LED lamp A.

The LED lamp according to the present invention is not limited to the foregoing embodiment. The specific structure of each part of the LED lamp according to the present invention may be changed in design in many ways. For instance, the shapes of the support substrate 1, the LED modules 2, the heat dissipation member 3 and the case 4 and so on are not limited to those described above. The manner of mounting the LED modules 2 on the support substrate 1 (e.g. the way of alignment, number and arrangement of the LED modules 2) is not limited to the foregoing embodiment.

In the foregoing embodiment, the movement of the heat dissipation member 3 is restricted by the paired projecting pieces 41 projecting from the inner side of the case 4 (see FIG. 2 ). Instead of this arrangement, a pair of projecting pieces 41′ as shown in FIG. 19 may be employed to restrict the movement of the heat dissipation member 3 and the support substrate 1.

In the foregoing embodiment, the arrangement of the LED modules is adapted to an LED lamp used as a substitute for a straight-tube fluorescent lamp. However, the present invention is not limited to this, and the arrangement of the LED modules may be adapted to an LED lamp used as a substitute for a circular fluorescent lamp or a downlight used as embedded in an indoor ceiling.

As the first through the third LED modules 2A, 2B and 2C, the LED modules shown in FIGS. 20-58 may be employed. These figures show the schematic outer configuration or directivity characteristics of each LED module. Each view showing the outer configuration of an LED module includes, from the top, a top view, a side view and a bottom view, and a right side view on the right of the top view. FIGS. 20-32 each shows an LED module with a reflector which can be employed as the first LED module 2A. The directivity characteristics of the first LED module 2A are such that the relative intensity RI is highest at the direction angle Da of 0°. FIGS. 33-42 each shows an LED module for sideways light emission which can be employed as the second LED module 2B. The directivity characteristics of the second LED module 2B are such that the direction in which the direction angle Da=0° corresponds to the outward direction within the plane of the mount surface 1 a of the support substrate 1. FIGS. 43-58 each shows an LED module with uniform intensity distribution which can be employed as the third LED module 2C. The directivity characteristics of the third LED module 2C are such that the relative intensity RI is not highest at the direction angle Da of 0°. It is to be noted that the LED modules shown in FIGS. 24 and 49 are of the type that emits two colors of light, whereas the LED modules shown in FIGS. 29, 39 and 57 are of the type that emits three colors of light.

The second direction is the thickness direction of the LED module, which is a direction normal to the mount surface 1 a. The third direction is the width direction of the LED module. The first direction is the length direction of the LED module, which is a direction perpendicular to a plane formed by the second direction and the third direction.

Instead of the above-described LED modules, bullet-shaped LED modules as shown in FIGS. 59 through 62 may be employed. The bullet-shaped LED module shown in FIG. 59 can be mounted on the support substrate 1 vertically or horizontally. Thus, by appropriately selecting the mounting orientation, the direction in which the relative intensity RI is highest can be set to correspond to the direction normal to the mount surface of the support substrate 1 or to the outward direction within the plane of the mount surface. The bullet-shaped LED module shown in FIG. 61 has a simpler structure as compared with the bullet-shaped LED module shown in FIG. 59 , and the directivity characteristics of this bullet-shaped LED module is such that the intensity of light is high in the direction normal to the mount surface of the support substrate 1. Instead of bullet-shaped LED modules shown in FIGS. 59 through 62 , use may be made of a conventional LED module having two lead pins. In using such a conventional LED module, the LED module is mounted by guiding each lead pin through the support substrate 1 or bending each lead pin. This allows the LED module to have directivity characteristics such that the intensity of light is relatively high in the direction normal to the mount surface of the support substrate 1 or the outward direction within the plane of the mount surface of the support substrate 1. 

The invention claimed is:
 1. An LED lamp that is configured to be fitted to a fluorescent lighting fixture having inlet ports, the LED lamp comprising: a substrate including first and second ends spaced from each other in a longitudinal direction of the substrate; a plurality of LEDs mounted on a mount surface of the substrate; a light-transmitting cover covering the plurality of LEDs; and a pair of bases attached to the first and second ends of the substrate, respectively, wherein each of the plurality of LEDs comprises: a first lead; a second lead spaced apart from the first lead in a first direction; a LED chip electrically connected to the first lead and the second lead; a case covering the first lead and the second lead in a manner such that the first lead and the second lead include bottom surfaces, respectively, that are flush with each other and are exposed from and in direct contact with lowest surface of the case, the lowest surface being flush with the bottom surfaces of the first lead and the second lead, the case surrounding the LED chip when viewed in a second direction perpendicular to a surface of the first lead; and a transparent sealing resin filled in a space defined by the case such that the LED chip is covered by the sealing resin, wherein the bottom surface of the first lead has a first area when viewed in the second direction, wherein the first area has a first length in the first direction and a first width in a third direction perpendicular to the first and second directions, the first width being constant in the first direction, wherein the first length of the first area is larger than the first width of the first area, wherein the bottom surface of the second lead has a second width in the third direction, wherein a maximum width of the first width is equal to the second width, and wherein each of the bases includes a pair of terminals each configured to be fitted into one of the inlet ports of the fluorescent lighting fixture.
 2. The LED lamp according to claim 1, wherein each of the LEDs has a thickness which is a dimension in a direction normal to the mount surface, a length which is a dimension along the first direction, and a width which is a dimension along a second direction perpendicular to the direction normal to the mount surface and the first direction, the thickness being smaller than the length and the width.
 3. The LED lamp according to claim 1, wherein the plurality of LEDs comprise a first group of LEDs arranged in a row along the longitudinal direction of the substrate and at a center of the substrate as viewed in the longitudinal direction.
 4. The LED lamp according to claim 3, wherein each of the first group of LEDs comprises a reflector configured to reflect light emitted from the LED chip of said each of the first group of LEDs.
 5. The LED lamp according to claim 1, wherein the first lead and the second lead of said each of the plurality of LEDs are bonded to a wiring pattern formed on the substrate.
 6. The LED lamp according to claim 1, wherein said each of the plurality of LEDs comprises a chip-substrate supporting the LED chip, and the case comprises a frame that is made of a white resin and extends upward from a periphery of the chip-substrate.
 7. The LED lamp according to claim 6, wherein in said each of the plurality of LEDs, the frame comprises a reflective surface surrounding the LED chip and the sealing resin.
 8. The LED lamp according to claim 1, wherein in said each of the plurality of LEDs, the sealing resin comprises: a silicone resin that transmits light from the LED chip; and a fluorescent material that emits yellow light when excited by blue light.
 9. The LED lamp according to claim 1, wherein the cover is semicircular or circular in cross section.
 10. The LED lamp according to claim 1, wherein in said each of the plurality of LEDs, each of the first lead and the second lead protrudes outward from the case in plan view.
 11. The LED lamp according to claim 1, wherein the bottom surface of the first lead further has a second area that extends outward in the first direction from the first area, the second area includes one outermost end and another outermost end that are spaced apart from each other in the third direction, a distance from the one outermost end to the another outermost end in the third direction is equal to or larger than the first width of the first area in the third direction.
 12. The LED lamp according to claim 1, wherein the bottom surface of the first lead further has second and third areas that protrude outward in the first direction from the first area, the second and third areas are overlapped with each other when viewed in the third direction, the second and third areas are overlapped with the case when viewed in the second direction.
 13. The LED lamp according to claim 12, wherein a portion of the case is exposed between the second area and the third area when viewed in the second direction.
 14. The LED lamp according to claim 1, wherein reflecting light from each of the plurality of LEDs has an angle spread of more than 60 degrees from the second direction.
 15. The LED lamp according to claim 1, wherein each of the plurality of LEDs is longer in the first direction than in the second direction, wherein each of the plurality of LEDs is mounted such that the first direction is parallel to the longitudinal direction of the substrate. 